The World Philosophy Made

by Scott Soames

  UNDERSTANDING NAMING, NECESSITY, AND CONCEPTUAL POSSIBILITY

  In January of 1970, a 29-year-old wunderkind, Saul Kripke (1941–), gave three lectures at Princeton University titled Naming and Necessity that changed the course of twentieth-century philosophy. At age 17, while still a high school student in Omaha, Nebraska, he had provided what was to become the first systematic and widely accepted semantics (theory of meaning) for formal systems of the logic of necessity and possibility—a problem that had been under investigation for nearly a quarter century starting with C. I. Lewis, C. H. Langford, Ruth Barcan Marcus, and Rudolf Carnap, among others.5 Having received his bachelor’s degree from Harvard in 1962, Kripke moved immediately to the Harvard Society of Fellows, spending alternate semesters lecturing first at Yale, and then at Princeton, before becoming a full-time research professor at Rockefeller University in New York.

  The chief achievement of the Princeton lectures was the development of a realistic, world-based conception of necessity and possibility, different from conceptual necessity and possibility. His main points can be illustrated using a few simple examples.

  1.  Greg Soames ≠ Brian Soames (SS: Greg and Brian are my two sons.)

  2.  If Saul Kripke exists, then Saul Kripke is a human being.

  3.  This desk (pointing at the one in my office) was not originally made of metal.

  4.  If this desk exists, then it is made of molecules.

  Since these propositions are true, they are, according to Kripke, necessarily true. Why? Well, Greg and Brian are two different people. Each could have existed without the other and each could have had different properties than he actually has. Greg could have been born in Princeton, New Jersey, rather than New Haven, Connecticut (where he was born). Brian could have been born in New Haven, rather than Princeton (where he was born). But the two of them couldn’t have both existed while being one and the same individual. If there were a possible individual GB, identical with both (i.e., the very same individual as both), then, since Greg and Brian actually exist while being nonidentical, GB would actually exist while being nonidentical with himself, which is absurd. Hence the fact that Greg and Brian are not identical (i.e., not the very same individual) means they couldn’t have been identical. It follows from this that the claim that they aren’t identical is a necessary truth.

  The point can be put by saying that nonidentity is an essential property of any pair of things that aren’t identical. Similarly, Kripke argued, being a human being is an essential property of anything that is a human being, which means that if Kripke really is a human being, then he couldn’t have existed without being a human being—in which case (2) is necessary, if true. So are (3) and (4). As it turns out, the desk in my office—this very one I am working on—is, and always was, made of wood, not metal. It is also composed of molecules. Like most things, it could have had some other properties it doesn’t in fact have. But being originally made of metal and not being composed of molecules are not among them. No matter what possible state the universe were in, if it contained a desk originally made out of metal, or if it somehow contained something that looked like and functioned as a desk, but was not composed of molecules, it would not be this very desk which I am working on now. Hence (3) and (4) are also necessary truths, if they are true at all.

  Although these points were, and are, elementary, they also were, and are, striking. Even though (1–4) are necessary truths, they are not true by definition, nor can they be known to be true by deducing them from self-evident truths (the negations of which are contradictory). On the contrary, they are knowable only on the basis of experience, observation, and empirical evidence. How can that be? How can a proposition that is necessary—and so would have been true no matter which state the world were in—require empirical evidence about the way that the world happens to be in order for it to be known?

  Kripke’s answer appeals to our knowledge of essential properties and relations. We know simply by understanding the terms ‘human’, ‘not (originally) made of metal’, and ‘composed of molecules’ that the properties they express—being a human, being something not (originally) made out of metal, and being composed of molecules—are essential properties of anything that has them. We also know, simply by understanding the nonidentity predicate, ‘≠’, that the relation, being nonidentical, it expresses holds essentially of any pair that are actually so related. In other words, we have antecedent conceptual, a priori knowledge that if any objects actually have these properties, or stand in the relation not being nonidentical to one another, then they would have those properties, or stand in that relation, in any genuinely possible circumstance in which they existed. Because of this, we have conceptual, a priori knowledge that propositions (1–4) are necessary, if true. Still, discovering that they are, in fact, true requires gathering empirical evidence. This means that to discover certain things that would have been facts no matter which possible state the world were in, we sometimes must first empirically investigate the state the world is in to discover whether they are facts. Similarly, in order to discover what could, or could not, possibly be, one must sometimes first investigate what is.

  This idea depends on a sharp distinction between conceptual and genuine possibility—i.e., between ways things could conceivably be versus ways things could really be (or have been). Following terminology adopted from Gottfried Leibniz, contemporary philosophers draw this distinction in terms of possible worlds, or better, possible world-states. For Kripke, possible world-states are maximally complete ways the real concrete universe could have been—maximally complete properties that the universe could have had. Conceptually possible world-states are maximally complete ways the universe can coherently be conceived to be—maximally complete properties the universe can be conceived to have—that one cannot know by reasoning alone (without empirical evidence) that it doesn’t have.

  These two sets of properties are different. Just as there are properties that ordinary objects could possibly have had and others they couldn’t have had, so there are certain maximally complete properties the universe could have had—genuinely possible world-states—and others the universe couldn’t have had—genuinely impossible world-states. Just as some of the properties that objects couldn’t have had are properties that one can conceive them as having, and that one can’t know a priori that they don’t have, so some maximally complete properties that the universe couldn’t have had—some impossible world-states—are properties one can conceive it as having that one can’t know a priori it doesn’t have. These states of the world are conceptually possible. Thus, empirical evidence required for knowledge of necessary truths like (1–4) is needed to rule out genuinely impossible, but conceptually possible, world-states in which they are false.

  Here is Kripke’s own formulation of the relationship between conceivability and genuine possibility.

  [W]e sharply distinguish between the notions of a posteriori and a priori truth on the one hand, and contingent and necessary truth on the other hand, for although the statement that this table, if it exists at all, was not made of ice, is necessary, it certainly is not something that we know a priori.… This looks like wood. It does not feel cold and it probably would if it were made of ice. Therefore, I conclude, probably this is not made of ice. Here my entire judgment is a posteriori … given that it is in fact not made of ice, in fact is made of wood, one cannot imagine that under certain circumstances it could have been made of ice. So we have to say that though we cannot know a priori whether the table was made of ice or not, given that it is not made of ice, it is necessarily not made of ice.… [I]f P is the statement that the table is not made of ice, one knows by a priori philosophical analysis, some conditional of the form “if P, then necessarily P.” If the table is not made of ice, it is necessarily not made of ice. On the other hand, then, we know by empirical investigation that P, the antecedent of the conditional is true—that this table is not made of ice. We can conclude by modus ponens:
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  P ⊃ Necessarily P

  P

  Necessarily P

  The conclusion—‘Necessarily P’—is that it is necessary that the table not be made of ice, and this conclusion is known a posteriori, since one of the premises on which it is based is a posteriori.6

  In Kripke’s argument, the fact that one can’t know a priori that P means that one can’t know a priori that a world-state in which it is false that P isn’t the state the world is actually in. Such states are coherently conceivable, and so conceptually possible. The fact that one knows a priori that if P, then necessarily P means one knows a priori that if a world-state in which it is true that P is actual, then no world-state in which it is false that P could have been actual. So, when one finds, empirically, that it is true that P, one learns that conceptually possible world-states in which it is false that P aren’t genuinely possible.

  With these clarifications in mind, we now return to the contention of proponents of the mind-body identity theory, who believed that widely accepted theoretical identities in physics, chemistry, and other sciences could serve as models for understanding empirically based statements identifying mental states and processes with physical states and processes. Remember, early proponents of mind-body identity believed that scientific identities are contingent, presumably because empirical evidence is needed to show them to be true. Not so, Kripke plausibly argued. Since gold is the very the same thing as the element with atomic number 79, gold couldn’t have existed without having that atomic structure. Consequently, the identity statement is a necessary truth. So are the statements that water is H2O and that heat is mean molecular kinetic energy. The former says that the substance water is the very same thing as the substance molecules of which contain two hydrogen atoms and one oxygen atom. Since this is a necessary truth, it follows that for any genuinely possible state, w, if the world had been in state w, then any quantity of water would have been a quantity of H2O, and conversely. Similarly in the case of heat, the truth of the identity claim guarantees that for any genuinely possible state, w, of the world, and for any pair x and y existing at w, if the world had been in state w, then x would have been hotter than y if and only if the mean molecular kinetic energy of the molecules of x would have been greater than that of those of y.

  When these lessons had been absorbed, Kripke and others concluded that statements identifying the mental with the physical must, like other scientific identity statements, be necessary, if true. This posed a problem because it was not clear that they could be so regarded.

  FUNCTIONALISM ABOUT THE MIND

  In order to determine the status of statements identifying mental states and processes with physical states and processes, we need to look more closely at mental concepts like pain. Since pains are conscious experiences, I am aware of my own pains in something like the way I am aware of my other conscious experiences (e.g., my visual or auditory experiences). I also know that my pains are caused by certain kinds of events, often injuries. Once caused, pains modify my thoughts, motivations, and actions in characteristic ways. Realizing all this about myself, I identify pain in others by observing their verbal and nonverbal responses to events similar to those that cause pain in me.

  These ideas can be used to build sophisticated functionalist analyses of the mind according to which the mental states of an organism are internal states that causally interact with one another in systematic ways to mediate sensory inputs and behavioral outputs.7 According to such analyses, sensory inputs interact with beliefs, desires, and preferences, often changing them and initiating action. Different mental states play different causal roles. Preferences assign high priority to certain outcomes. Believing that so-and-so typically leads to behavior that brings about highly valued outcomes in situations in which it is true that so-and-so. Desiring that so-and-so—e.g., that one finds one’s misplaced car keys—often leads to actions one believes will bring it about that so-and-so—e.g., that one finds the keys. Fitting pain into this picture means thinking of it as a kind of internal perception of bodily injury that an agent has a high preference for avoiding. Normally, this perception leads to actions intended to minimize the injury, and to intentions to avoid similar injury in the future.

  Generalizing, we may say that a datable event or state of an organism is a pain if and only if it is an internal state of detecting injury, instances of which play a certain functional role in the life of an organism. In the interest of avoiding false precision, let us simply call this “the pain role.” The state designated by ‘pain’ is then the internal perceptual state of an organism o the function of which is to detect injury to o, instances of which typically play the pain role in o. The predicate ‘is a pain’ is true of all and only instances of that state—i.e., of all and only the experiences of so perceiving and playing that role in an organism.

  According to this analysis, it is highly probable that which physiological states count as pains varies from one kind of organism to the next. Presumably mammals, reptiles, fish, members of now extinct species, and members of species that may or could evolve in the future are capable of feeling pain. What they all have in common is an internal perceptual state the function of which is to detect bodily injury, to trigger changes in their motivational states that normally lead to actions intended to end or minimize the current injury, and to generate or reinforce desires and intentions to avoid similar injuries in the future.

  This, I submit, fits our concept of pain pretty well. If this is what pain is, then something along the lines of the theoretical identity statement (5) is both true and necessary.

  5.  Pain in an organism o is the state in o that plays the pain role.

  If it is also true that there are many organisms capable of feeling pain, despite having vastly different internal physiologies, then it is highly unlikely that there is a single physiological state, describable in the language of neuroscience, that can be identified with pain in every creature capable of feeling pain. It may turn out that for each different type T of creature, there is a physical state described by a phrase XXX in the language of neuroscience that makes (6) true, but there is no single choice of XXX that makes (6) true for all types of creatures.

  6.  For all individual organisms o of type T, and for all internal states y of o, y is a state of o’s being in pain if and only if y is a neurophysiological state of type XXX.

  If this is right, then pain is a functional state, not one particular kind of physical state. Still, you may ask, Are pains in human beings purely physical events, or not? To answer this question, we must look further.

  A FAILED ARGUMENT AGAINST IDENTIFYING HUMAN PAINS WITH NEUROPHYSIOLOGICAL EVENTS

  One of the best known arguments against the psychophysical identification of human pains with neurological C-fiber stimulation is based on Kripke’s discussion of statements like (7) and (8a) in Naming and Necessity.

    7.  Human pain = C-fiber stimulation

  8a.  Heat = mean molecular kinetic energy

  Noting that both initially seem to be contingently true, or contingently false, Kripke insisted that both must be necessary, if true. Although this was not, he thought, a problem for the genuine necessity of (8a), it was, he thought, a problem for the (alleged) necessity of (7).

  The illusion that (8a) is contingent is, he speculated, rooted in the fact that we identify heat indirectly, by the sensations it causes in us. Because of this, he argued, we associate ‘heat’ with the reference-fixing description ‘the cause of a certain sensation S’. Taking this sensation to be part of “our concept of heat,” Kripke argued that we wrongly mistake the description for a synonym for ‘heat’, leading us to confuse the necessary truth (8a) with the contingent truth (8b).

  8b.  The cause of sensation S = mean molecular kinetic energy

  Since many things could have been hot, even if there were no sentient beings capable of having sensations, (8b) could, genuinely, have been false. Thus, Kripke concluded, our confusion of (8a
) with (8b) wrongly led us imagine that (8a) could, genuinely, have been false.8 Once this error is pointed out, however, we can accept that (8a) must be necessary, if it is true at all.

  Kripke argued that the same strategy can’t be used to dismiss the impression that humans could, genuinely, have experienced C-fiber stimulations without pain. Unlike heat, we designate pain directly. We don’t say, “What a horrible sensation! Let’s use ‘pain’ to refer to whatever causes it.” Rather, we use ‘pain’ to designate the sensation itself. Since we don’t use any description to fix the referent of the word ‘pain’, there is no such reference-fixing phrase to confuse with a synonym for ‘pain’, and no contingent truth to confuse with (7). Consequently, we can’t dismiss the impression that if (7) is true, it is contingent as an illusion. On the contrary, if (7) is true, it must be contingent. Since, in fact, Kripke thought he had shown that all theoretical identity statements of this general sort are necessary if true, he suggested that (7) is false.

  This argument fails for two reasons. The first results from mischaracterizing the “illusion of contingency” carried by true theoretical identity statements that really are, as Kripke insists, necessary truths. The mischaracterization is applied to (7) and (8a) on the basis of a questionable contrast between how we identify heat versus how we identify pain. Although there is a contrast, it’s not the one Kripke suggests. The most basic contrast is that whereas heat is something we perceive, pain is our perception of something. Our sensation of heat is our perception of heat; it is a special kind of experience that reliably, but fallibly, detects heat. Similarly, our pain sensation is our perception of injury; it is a special kind of perceptual experience that reliably, but fallibly, detects injury (think pain in phantom limbs). The reason there is no pain without “an experience of pain” is that pains are perceptual experiences.